This is a revised application from Wills Eye Hospital to participate in the Advanced Glaucoma Intervention Study (AGIS). Our qualifications to participate in AGIS are detailed, including patient availability. During the 18-month period ending June, 1986 56 AGIS-eligible eyes were treated by one of us (a rate of 38 elibible eyes a year). Since June 1986 our surgical capacity has increased. The principal investigator has joined the Wills Eye Hospital staff and treated 14 eligible eyes (28 eligible eyes a year). Both investigators are now involved with resident service patients, with an expected 15 eligible eyes a year. We, therefore, expect a total of 80 eligible eyes a year. With a 50% recruitment rate, 40 eyes should enter a year. The primary goal of the AGIS is to assess systematically the long- range outcomes of sequences of interventions in 840 eyes that have failed initial medical treatment of glaucoma. Eligible eyes will be randomly assigned to one of two intervention sequences; 1) trabeculectomy (T), followed by argon laser trabeculoplasty (ALT) should T fail, and followed by a second T should ALT fail; and 2) ALT followed by T should ALT fail, and followed by another T should the first T fail. Eyes that fail the assigned sequence of three interventions will be managed by additional surgery. The interventions will be supplemented with medical treatment as needed. We plan to follow all patients for five years to determine degree of visual function loss, rates of failure of interventions and intervention sequences, rates of complications, and need for supplemental therapy. The prognostic value of ocular, systemic, personal, and social factors, including compliance, will be studied. Participating institutions will adhere to common, specified definitions, eligibility criteria, methods of measurement, as well as diagnostic, treatment, quality control, and administrative procedures. A Coordinating Center will collect, process, and analyze study data and coordinate study activities; a Policy and Treatment Effects Monitoring Board will supervise the conduct of the study.